Dear All
I am working with
GNU Prolog 1.3.1
By Daniel Diaz
Copyright (C) 1999-2009 Daniel Diaz
It seems that escapes in backquoted strings are
detected, but not converted.
Normal single quotes:
?- X = 'abc'.
X = abc
| ?- X = '\''.
X = ''''
?- X = '\x61\'.
X = a
Back quotes:
?- X = `abc`.
X = abc
?- X = `\'`.
X = '\\'''
?- X = `\x61\`.
X = '\\x61\\'
It seems that the escapes are not converted. But
they are detected during parsing of backquoted
strings, at least the first escaped character is
always expected:
?- X = `\`.
.
uncaught exception: error(syntax_error('user_input:10 (char:8)
expression expected or previous operator needs brackets'),read_term/3)
But the closing escape character of a noctal or
hexadecimal constant seems not to be not expected:
?- X = `\x61`.
X = '\\x61'.
?- X = `\0`.
X = '\\0'
From my understanding of ISO standard for back quoted strings,
the same escaping rules should hold as for single quoted
strings. I am referening to non quote char (* 6.4.2.1 *).
Is this a bug or a feature?
Bye
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